Bulk material silos have several types of discharge equipment such as screw feeders, rotary valves, butterfly valves, slide gate valves, chain conveyors, bulk truck loading bellows and pneumatic conveying systems. Depending on application, there are wide range of receiving points like bins, processing lines, weighing and batching systems, trucks, mixers etc. Silo discharge control systems provide full control over silo discharging equipment for efficient handling.
System is connected to level and pressure sensors, vibrating bin activators, dischaarging equipment, DCS or SCADA system and downstream equipment. Product discharge is controlled with respect to process requirements. If a truck is to be loaded, system is connected to truck loading bellow and stops when the truck is full. If a mixer is to be filled with the help of weighing unit, system stops when the desired filling amount is reached. If a pneumatic conveying system is connected to another bin, system stops when the bin is full.
Silo discharge control system also monitors the pressure inside the silo. If the silo unloading speed is high,powdered material inside the silo moves down rapidly and creates negative pressure (vacuum) above itself. If the level of negative pressure is high enough, it may cause the silo to collapse inwards. Silo control system can also monitor the silo inner pressure level and stops discharging if when the vacuum level is critical.